Question
Write the method called printTriangleType referred to in Self-Check Problem 22. This method accepts three integer arguments representing the lengths of the sides of a triangle and prints the type of triangle that these sides form. Here are some sample calls to printTriangleType:
printTriangleType(5, 7, 7);
printTriangleType(6, 6, 6);
printTriangleType(5, 7, 8);
printTriangleType(2, 18, 2);
The output produced by these calls should be
isosceles
equilateral
scalene
isosceles
Your method should throw an IllegalArgumentException if passed invalid values, such as ones where one side’s length is longer than the sum of the other two, which is impossible in a triangle. For example, the call of printTriangleType(2, 18, 2); should throw an exception.
Answer
Program:
public class Ch04Ex09
{
public static void main(String[] args)
{
printTriangleType(5, 7, 7);
printTriangleType(6, 6, 6);
printTriangleType(5, 7, 8);
printTriangleType(2, 18, 2);
}
public static void printTriangleType(int side1, int side2, int side3)
{
if(side1 > side2 + side3 || side2 > side3 + side1 || side3 > side1 + side2)
{
throw new IllegalArgumentException("Invalid sides in a triangle!");
}
if (side1 == side2 && side2 == side3)
{
System.out.println("equilateral");
}
else if (side1 == side2 || side2 == side3 || side1 == side3)
{
System.out.println("isosceles");
}
else
{
System.out.println("scalene");
}
}
}
Output:
isosceles
equilateral
scalene
Exception in thread "main" java.lang.IllegalArgumentException: Invalid sides in a triangle!
at Ch04Ex09.printTriangleType(Ch04Ex09.java:15)
at Ch04Ex09.main(Ch04Ex09.java:8)